Arcing or arc fault is an electrical discharge through a normally nonconductive gas, usually air. Such arcing can occur between exposed conductors of different electrical potentials, typically between adjacent busbars or between a busbar and ground in low-voltage electrical distribution equipment. When an arc jumps from one conductor to another across an air gap, it can produce extremely hot gasses, vaporized metals/polymers, and other harmful byproducts. Although the arc must remain in contact with the conductors to be viable, the shape of the arc can stretch and wrap around obstacles to follow the path of least resistance across the air gap.
The hazards of unexpected and/or uncontrolled arcing are well known and include potential damage to equipment and harm to personnel in the operating environment caused by arc flash and arc blast, hereinafter referred to for simplicity as arc blast. Techniques for controlling arcing are known in the art, including passive and active arc control techniques. Active arc control techniques usually include some form of sensing and a switching mechanism to control the arc current. Concerns with active techniques may include higher cost, nuisance breaker trips, speed, and undetected system failures. Passive techniques may include containment and directed venting of the arc blast energy and gasses out of the equipment cabinet. Other passive arc control techniques may include reinforcement of the cabinet structure in an effort to withstand the blast. Neither of the above passive methods limits the duration of the arcing event.
Thus, a need exists for an improved way to control and limit the damage caused by arcs in electrical distribution equipment and particularly arcs on exposed conductors such as between two busbars or a busbar and ground in the electrical distribution equipment.